Liquid Crystal Infiltrated Anti-Resonant Reflecting Waveguide for Electric Field Sensing

An electric field (E-field) sensor based on liquid crystal (LC) infiltrated hollow core photonic crystal fiber (PCF) is proposed and experimentally demonstrated. The liquid crystal (5CB nematic liquid crystal, NLC) is selectively infiltrated into one of the cladding air holes of a simplified hollow-core photonic crystal fiber (SHCPCF) using the femtosecond laser assisted selectively infiltration method. A double layer anti-resonant reflecting waveguide consisting of the LC layer and silica layer is then formed. Applying external E-field to the NLC-filled SHCPCF will alter the alignment of liquid crystal molecules in the LC layer, which further affects the anti-resonant reflection guiding mechanism. In the range of 100 V to 200 V (0.5 kV/mm to 1.0 kV/mm), an E-field sensitivity of about 30.34 dB/kV/mm is achieved. The temporal characteristic of the E-field sensing is also investigated, and the sensor exhibits response time of about approximately 286 ms, and recovery time of about 195 ms. The proposed sensor is lightweight, cost effective, highly sensitive with fast response, which can be finding wide applications in industrial productions.